Weft-injection system for shuttleless loom

ABSTRACT

Two counteroscillating lances on opposite sides of a set of warp threads serve for the unidirectional transportation of a succession of weft carriers across the shedded warp, one lance pushing each weft carrier from the insertion side to about the middle of the shed where the carrier is transferred to the other lane pulling it through the remainder of the shed to the extraction side. The retrieved carriers are returned, in the order of their arrival at the extraction side, to the insertion side by a conveyor mechanism synchronized with the lance drive. The reciprocating strokes of the two lances are relatively dephased so that the inserting lance moves briefly in the same direction as the extracting lance at the instant of transfer.

United States Patent Conte et al.

WEFT-INJECTION SYSTEM FOR SHUTTLELESS LOOM Inventors: Georges Conte,

Villeurbanne-Rhone; Pierre Royer, Vaulx-en-Velin-Rhone; Edmond Narboux,Bron-Rhone, all of France Mecoutil Societe a Responsibilite Limitee,Anatole, France Filed: May 30, 1973 Appl. No: 365,077

Assignee:

US. Cl. 139/126, 139/141 Int. Cl D03d 47/12 Field of Search 139/122,123, 125, 126,

References Cited UNITED STATES PATENTS 3,603,352 9/1971 Golobart 139/127Primary ExaminerHenry S. Jaudon Attorney, Agent, or Firm1(arl E. Ross;Herbert Dubno [57] ABSTRACT Two counteroscillating lances on oppositesides of a set of warp threads serve for the unidirectionaltransportation of a succession of weft carriers across the shedded warp,one lance pushing each weft carrier from the insertion side to about themiddle of the shed where the carrier is transferred to the other lanepulling it through the remainder of the shed to the extraction side. Theretrieved carriers are returned, in the order of their arrival at theextraction side, to the insertion side by a conveyor mechanismsynchronized with the lance drive. The reciprocating strokes of the twolances are relatively dephased so that the inserting lance moves brieflyin the same direction as the extracting lance at the instant oftransfer.

10 Claims, 19 Drawing Figures PATENTED JANZI I975 SHEET 2 OF 3 i 3 mw mv WiQ L: mm mm AAA/A WEFT-INJECTION SYSTEM FOR SHUTTLELESS LOOM FIELD OFTHE INVENTION Our present invention relates to a loom of the shuttlelesstype in which a weft carrier is transported through a shedded set ofwarp threads with the aid of two Iances entering the shed from oppositesides.

BACKGROUND OF THE INVENTION In conventional looms of this type the twocounteroscillating Iances move halfway into the shed toward each other,one lance pushing the carrier ahead until it encounters the other lanceto which it is then transferred for extraction from the shed. Thecarrier, dragging its weft thread behind it, moves back and forththrough the changing shed into which it is alternately inserted from theleft and from the right, each lance acting alternately as a pusher andas a puller.

Although such systems operate satisfactorily in principle, they arerelatively complex in their construction. In particular, the mechanismfor alternately transferring the weft carrier from the left lance to theright lance and then from the right lance to the left lance is somewhatinvolved.

OBJECTS OF THE INVENTION The general object of our present invention isto provide a simplified weft-injection system for a loom of thecharacter referred to.

A more specific object is to provide a smoothly operating mechanism fortransferring a weft carrier from one lance to another in a system ofthis character.

SUMMARY OF THE INVENTION These objects are realized, in accordance withthe present invention, by providing each weft carrier with firstcoupling means engageable by a first lance, hereinafter referred to asthe inserting lance, and with second coupling means engageable by thesecond lance, hereinafter referred to as the extracting lance, thesecond coupling means overriding the first coupling means in a positionof momentary simultaneous engagement of a weft carrier by both Ianceswhereby, upon subsequent separation of the Iances, the carrier remainsengaged with the extracting lance after having been introduced into theshed by the inserting lance. Thus, the carrier motion is invariably fromthe first lance to the second one, i.e., from an insertion side to anextraction side, the carriers being conveyed back from the extractionside to the insertion side by transport means synchro nized with thelance drive but bypassing the warp threads. Upon returning to theinsertion side, each carrier passes a loading device which attaches afresh weft thread to it for entrainment across the shed.

According to a more specific feature of our invention, the weft carrierhas a pair of oppositely facing sockets for matingly receivingrespective tips of the two Iances; each tip has a resilient orspring-loaded tongue carrying a lug which fits into a peripheral recessof the corresponding socket to hold the lance engaged. However, the lugof the inserting lance has a sloping edge enabling it to be cammed outof its recess whereas the lug of the extracting lance has a straightedge holding it positively engaged in its recess. To disengage theextracting lance from the weft carrier, a release mechanism at theextraction side acts upon a camming formation on the tongue of thatlance to withdraw the lug. The camming mechanism also operates tounclamp the entrained weft thread from the carrier.

In accordance with a further feature of our invention, the weft clamp ofthe carrier is normally closed and has a movable jaw rigid with aswingable guard plate which extends parallel to the direction of carriermotion; this jaw is urged toward an associated fixed jaw by springmeans, such as a stack of leaf springs, which also cause a tilting ofthe guard plate into such a position that the weight of this platesupplements the spring force to hold the clamp closed.

Advantageously, pursuant to yet another feature of our invention, thetwo Iances are driven by respective cranks which are relatively dephasedto an extent letting the two lances move codirectionally and atapproximately the same speed at the instant of simultaneous engagementof a weft carrier midway in the shed. This codirectional lance movementensures a smooth transfer of the weft carrier from the inserting lanceto the extracting lance. It thus becomes possible to drive the Iances atan accelerated rate within the shed and to slow them down in the regionof the shed edges, i.e. at the points of detachment of a previouslyentrained weft thread and attachment of a new weft thread.

BRIEF DESCRIPTION OF THE DRAWING The above and other features of ourinvention will now be described in detail with reference to theaccompanying drawing in which:

FIG. 1 is a side-elevational view of a weft carrier according to ourinvention;

FIG. 2 is a top plan view of the carrier shown in FIG.

FIG. 3 is a longitudinal sectional view of the carrier taken on the lineIII III of FIG. 2;

FIG. 4 is a front view of a fixed clamp jaw forming part of the carrierof FIGS. 1 3;

FIG. 5 is a bottom view of the clamp jaw shown in FIG. 4;

FIG. 6 is a cross-sectional view taken on the line VI VI of FIG. 1,showing the weft clamp of the carrier in its open position;

FIG. 7 is a view similar to FIG. 6, showing the clamp in closed positionand illustrating a guide element for the carrier;

FIG. 8 is a plan view similar to FIG. 2 but showing only the base of theweft carrier with its superstructure removed;

FIG. 9 is a longitudinal sectional elevation of an extracting lanceengageable with the carrier of FIGS. 1 8, taken on the line 9 9 of FIG.10;

FIG. 10 is a top view of the lance shown in FIG. 9;

FIG. 11 is a view analogous to FIG. 9, taken on the line 11 ll of FIG.12 and showing an inserting lance;

FIG. 12 is a top view of the lance shown in FIG. ll;

FIG. 13 is a view analogous to FIGS. 9 and 11, taken on the line 13 13of FIG. 14 and showing the assembly of the two Iances and the weftcarrier;

FIG. 14 is a top view of the assembly of FIG. 13;

FIG. 15 is an end view of a loom embodying the components of FIGS. 1 14;

FIG. I6 is a partial top view of the loom shown in FIG. 15;

FIG. 17 is a sectional detail view of part of the driving mechanism forone of the Iances;

FIG. 18 is a top view of the assembly shown in FIG. 17; and

FIG. 19 is a face view thereof.

SPECIFIC DESCRIPTION Reference will first be made to FIGS. 15 and 16which show the principal parts, to the extent here material, of a loomembodying our invention. The loom comprises a frame with two lateralhalves 100 and 100" interconnected by braces 101 (only one shown), hallI extending along the insertion side of a set of warp threads 31 (seeFIGS. 6 and 7) which pass through a reed 118 on a batten 116. A supplyof weft threads is diagrammatically represented by a spool 123 disposedon the insertion side of the loom, a thread 25 from this spool being fedto a loading station 122; The latter, in a manner known per se, liftsthe free end of the thread into the path of a weft carrier 1, shown inFIGS. 1 8, l3 and 14, which seizes the thread and transports it throughthe shed of the warp. Upon the completion of a traverse, loader 122clamps the thread 25 in place, cuts off the inserted part thereof andpresents a new length of thread to the next weft carrier programmed toinsert an identical filling into the warp.

The loom frame further comprises mountings 102', 102" for the drivemechanisms of two counteroscillating lances, namely an inserting lance36 on the left and an extracting lance 55 on the right. Details of thesedrive mechanisms will be described later. Their source of power is a camshaft 106, continuously rotated by a nonillustrated motor, whichcontrols the swing of the batten 116 in conventional manner through arocker shaft 125 and a set of arms 117 supporting the batten on thatshaft. A weft carrier aligned with lance 36 on the insertion side of thewarp, i.e., above frame half 100', is pushed by that lance into the shedafter having been loaded with a thread 25. Substantially midway withinthe shed, the carrier is transferred to the lance 55 which thereuponpulls it through the remainder of the shed.

An ancillary shaft 119, also driven from shaft 106, operates a pair ofbucket chains 121 and 121" on opposite sides of the warp. Chain 121", onthe extraction side, picks up each oncoming weft carrier as it isdisengaged from lance 55 and detached from the entrained weft, feedingit to an endless compartmented belt 120 which conveys it to chain 121for delivery to the loading station 122. The conveyor system 120, 121,121" is so synchronized with the lance drives and the batten swing thata fresh weft carrier always appears in line with the withdrawn insertinglance 36 upon the formation of each new shed. Thus, the weft carrierspass unidirectionally through the shed and are continuously returned tothe insertion side via the conveyor belt 120 bypassing the warp.

We shall now describe, with reference to FIGS. 1 8, the construction ofa weft carrier 1 designed to cooperate with the two lances 36 and 55 inthe manner broadly discussed above.

The weft carrier 1, whose body may consist of plastic material, has aforwardly open front socket 2 and a rearwardly open back socket 4 ofrectangular crosssection. A central well 3 accommodates a hinge plate 5(FIGS. 2, 3 and 6-8) with pintles l3 and 14, centered on a longitudinalswing axis, received in respective recesses l2 and 11. Hinge plate 5 isfastened to a guard plate 6 and is integral with a spur 7 forming amovable clamp jaw for a weft thread 25. Jaw 7 carries an elastic toplayer 32 which confronts a serrated surface portion 26 on the undersideof a plate 20 constituting a coacting fixed clamp jaw. Plate 20, whichforms the upper boundary of socket 4 and is held in position by screws20', is provided with a cutout 22 acting as a recess in the socket wall;a similar cutout 19 is formed in a plate 18 which constitutes the upperboundary of socket 2. It should be noted, however, that the transverseedges of cutout 22 are beveled whereas those of cutout 19, particularlyits leading edge 72, are straight. Plates 18 and 20 advantageouslyconsist of stainless steel.

A large cutout 8 in the bottom of well 3 serves for the discharge oflint and other matter that may accumulate in operation.

Plate 20, which carries a depending weft-guiding pin 27 entering a blindbore 28 in the body of carrier 1, terminates in a sloping lug 21 servingto guide the weft thread into the clamp constituted by jaws 7 and 20. Asbest seen in FIG. 2, the thread 25 picked up by the lug 21 comes to restagainst a rounded corner 33 at an edge of the lug and passes around thepin 27. Jaw 7 is urged upwardly by a stack of leaf springs 10, partlyseated in a groove 9, and by the weight of the guard plate 6 in itsnormal position (FIG. 7) in which this plate is tilted slightlyoutwardly; the longitudinally extending serra tions 26 serve to hold thethread firmly against the yieldable contact surface 32. Guard plate 6and a similar, slightly lower plate 29 at the opposite carrier edgeserve to prevent any entanglement between the lug 21 and the warpthreads 31 (FIGS. 6 and 7) at the upper boundary of a shed traversed bythe carrier 1. Plates 6 and 29 advantageously also consist of stainlesssteel; plate 29 has a hump 30 in the region of lug 21. FIG. 6illustrates an off-normal erect position of the guard plate into whichit is cammed by a ramp 34 (see also FIG. 15) that is adjustably mountedon the extraction side of the frame to unclamp the entrained weft thread25 upon the completion of the traverse.

The bottom of carrier 1 is formed with lateral ribs 15, 16 which fitinto undercuts of a series of brackets 17 (see also FIG. 14) mounted onthe batten 116 adjacent its reed 117. The brackets 17, which are alignedwith respective reed bars so as not to interfere with the movement ofthe warp, are spaced apart in the direction of carrier motion by lessthan the length of ribs 15, 16 so as to form a track for the continuousguidance of the carrier. The same track guides the lances 36 and 55which are provided for this purpose with respective ribs 53 and 82; seeFIGS. 9 14.

We shall now describe, with reference to FIGS. 9 14, the co-operation oflances 36 and 55 with weft carrier 1.

FIGS. 9 and 10 illustrate the extracting lance 55. The body of thislance, like that of lance 36 described hereinafter with reference toFIGS. 11 and 12, is a tube of square cross-section provided at itsdriven end with a projecting bolt fixed in position by screws 79. Bolt80 is partly screwed into a threaded sleeve 57 terminating in an eye 58"which accommodates a crank pin as seen in FIGS. 15 and 16; the effectivelength of the lance 55 can be adjusted by varying the extent ofpenetration of bolt 80 into sleeve 57. The adjusted position ismaintained by a nut 81 bearing upon the sleeve 57.

Fixedly seated in the free end of lance 55 is an elon gated couplingmember 56 bracketed by lateral flanges 77, 78 of the lance body and heldin position thereon by screws 59. The cross-section of a reducedprojecting extremity 60 of member 56 corresponds to that of socket 2 ofweft carrier 1 which is open toward this member. A longitudinal channel73 of member 56 provides room for a tongue 61 which is riveted at 64 tothe uppermost leaf spring 65 of a stack of such springs held in place,beyond member 56, by screws 69. The left hand end of tongue 61 carries ahook-shaped lug 62 with a vertically disposed right-hand flank 70 and asloping left-hand flank 71, the latter flank being cammingly engageableby the front plate 18 of carrier 1 to depress the tongue 61substantially to the bottom of socket 2 as the carrier approaches thelance for engagement therewith. Upon full insertion of the tip 68 ofmember 56 into socket 2, hook 62 rises into the recess 19 of plate 18for positive interlocking therewith as its steep flank 70 comes to restagainst the edge 72 of the recess. It should be noted that the end 66 oftongue 61 is overlain by a ledge 67 of the tip 68 and normally engagesthis ledge from below, thereby limiting the rise of hook 62 under thestress of springs 65.

The right-hand end of tongue 61 is integral with a boss 63 of generallytrapezoidal profile, defined by sloping flanks 74, 75 and asubstantially level crest 76, which rises above the body of lance 55 forco-operation with a stud 124 (FIG. fixedly positioned on frame half 100"above the path of lance 55. Thus, a withdrawal of this lance to itsextreme right-hand position causes the stud 124 to depress the tongue 61against the force of springs 65 whereby hook 62 is disengaged fromrecess 19 and the lance is decoupled from the carrier 1. This occurssubstantially at the same time that ramp 34 coacts with guard plate 6 toswing the same into its upright position of FIG. 6 with consequentrelease of thread by clamp 7, 20.

Inserting lance 36, as seen in FIGS. 11 and 12, has a constructionsimilar to but not identical with that of lance 55. Its driven end isalso provided with a bolt 51, held in position by screws 50, which isscrewed into a threaded sleeve 38 to enable adjustment of the effectivelength of this lance; a nut 52 holds the sleeve in the selectedposition. Sleeve 38 has an eye 58 accommo dating a crank pin 105', shownin FIG. 16.

Fixedly seated in the free end of lance 36 is an elongated couplingmember 37 bracketed by lateral flanges 48, 49 of the lance body, thecross-section of a reduced projecting extremity 54 of this membercorresponding to that of the confronting socket 4 of weft carrier 1.Member 37, held in position by screws 49, forms a longitudinal channel,similar to channel 73 of member 56, accommodating an elastic tongue 41which has a fixed end clamped between blocks 23, 24 with the aid ofscrews 43. The mobile end of tongue 41 has a rightward extension 41aprovided with a lug 42 having sloping right and left flanks 46 and 47;the end 44 of tongue extension 4la is overlain by a ledge 45 formed bythe tip 40 of member 37, this ledge being normally engaged by the end 44and limiting the rise of lug 42 under the inherent spring force oftongue 41. The sloping flanks of lug 42 enable the introduction of tip40 into socket 4 with downward depression of this lug until it alignsitself with recess 22, the lug entering this recess for operative butnot positive coupling of lance 36 with carrier 1. Thus, upon thesubsequent positive engagement of the carrier with lance 55, thedivergent motion of the two lances leaves the carrier connected withlance 55 while detaching it from lance 36 as the lug is cammeddownwardly so as to depress the tongue extension 41a substantially tothe bottom of the socket 4. With the configuration described andillustrated, therefore, the positive coupling 19, 62 of the extractinglance overrides the yieldable coupling 22, 42 of the inserting lance 36.

Lateral flanges 77, 78 and 48, 49 have sloping edges serving to deflectany warp threads encountered by the advancing lance. Flanges 48, 49 alsoact to elevate the thread holder of station 122 above the lance body atthe commencement of an insertion stroke.

FIGS. 13 and 14 illustrate a brief instant during which the carrier 1 isengaged by both lances, this being the moment of transfer from theinserting lance to the extracting lance and occurring approximatelymidway in the shed. It will be noted that guard plate 6 has a curvedextremity 35 overlapping the flange 77 of lance 55 to form therewith asubstantially continuous ridge so as to ward off any overlying warpthreads that might otherwise become entangled with projecting formationsof the carrier traversing the shed.

Advantageously, in the position shown in FIGS. 13 and 14, the two lances36 and 55 move codirectionally and at nearly the same speed in order tobring about a smooth transfer. This is accomplished, in accordance witha feature of our invention, by driving the two lances 36 and 55 notexactly in phase but with a slight angular offset as illustrated in FIG.16. Thus lance 36 is reciprocated, through a pitman 103, by a crank 104lagging by a few degrees (with reference to the fully withdrawnposition) behind a similar crank 104" driving the lance 55 through apitman 103". As a result, the lance 55 introduced into the shed willhave begun its rightward return stroke when the lance 36 reaches the endof its insertion stroke; hook 62 snaps into engagement with recess 19just as the lance 55 leaves dead center and accelerates even as lance 36slows down to zero speed.

Furthermore, the drive mechanisms for cranks 104' and 104" are designedto rotate these cranks at nonuniform speeds to accelerate the lancemotion (as compared with ordinary crank drives) within the shed and toretard them at the opposite ends of their strokes, i.e., in thepositions in which weft carriers are picked up by the lance 36 or arereleased by the lance 55. FIG. 15 shows the drive mechanism 109 forcrank 104", within mounting 102", which is identical with thenonillustrated drive mechanism for crank 104 within mounting 102'.Mechanism 109 includes a shaft 110 driving the crank 104" through a pairof bevel gears 108, shaft 110 being in turn driven by main shaft 106 viaan eccentric coupling best illustrated in FIGS. l719. The couplingincludes a disk 107, rigid with shaft 106, carrying a roller 112 whichengages in a groove 113 of a radially extending arm 114 fixed to shaft110; the axes of shafts 106 and 110 are relatively offset so that roller112 has a large moment arm in the withdrawn position of the lance (asillustrated in FIGS. 15 to 19) but a small moment arm in the oppositeposition. Disk 107 also serves as a sheave for driving the shaft 106, byway of conventional V-belts, from its nonillustrated motor.

Gear trains interconnecting shafts 106, 119 and are disposed in atransmission housing 115. FIG. 15 also shows guides 111 for lance 55which are similar to brackets 17 (FIGS. 7 and 13) and which areduplicated on the other side of the loom for the guidance of lance 36.

The relative acceleration of the lance motion over a major part of atraverse provides a longer period for the operation of the batten, aswell as of the associated heddles, whose control cams may therefore bedesigned to drive these components in a manner minimizing the generatedshocks.

We claim:

1. In a loom having shed-forming means for a set of warp threads on aframe and a supply of weft threads on one side of the set, thecombination therewith of:

a first lance reciprocably mounted on said frame for introduction intothe shedded warp threads from said one side to substantially the middleof the shed;

a second lance reciprocably mounted on said frame for introduction intothe shedded warp threads from the opposite side to substantially themiddle of the shed;

a plurality of weft carriers each provided with weftgripping means, eachweft carrier having first coupling means engageable by said first lancefor insertion thereby from said one side into the shed and secondcoupling means engageable by said second lance for extraction therebyfrom the shed at said opposite side;

drive means for simultaneously reciprocating said lance in oppositedirections and in aligned relationship with momentary simultaneousengagement of a weft carrier by both lances substantially midway of theshed, said second coupling means overriding said first coupling meanswhereby the weft carrier remains engaged with said second lance uponsubsequent separation of said lances;

release means at said opposite side for detaching an oncoming weftcarrier from its weft and from said second lance;

transport means on said frame for conveying the detached weft carrierfrom said opposite side around said set of warp threads to said oneside; and

loading means at said one side for attaching a fresh weft thread to anarriving weft carrier prior to in sertion thereof into the shed by saidfirst lance.

2. The combination defined in claim 1 wherein said weft-gripping meanscomprises a normally closed clamp with a fixed jaw and a movable jaw,said release means including a trip member on said frame at saidopposite side engageable with said movable jaw.

3. The combination defined in claim-2 wherein said weft carrier isprovided with a swingable guard plate extending parallel to itsdirection of movement across the shed, said movable jaw being rigid withsaid guard plate.

4. The combination defined in claim 3 wherein said movable jaw isprovided with spring means urging same toward said fixed jaw Whileholding said guard plate in a tilted position in which the weight ofsaid guard plate supplements the force of said spring means.

5. The combination defined in claim 1 wherein said first coupling meanscomprises a rearwardly open socket of the weft carrier provided with afirst peripheral recess and wherein said second coupling means comprisesa forwardly open socket of the weft carrier provided with a secondperipheral recess. said first lance having a tip matingly receivable insaid rearwardly open socket and provided with a first tongue carrying afirst lug fitting into said first recess, said second lance having a tipmatingly receivable in said forwardly open socket and provided with asecond tongue carrying a second lug fitting into said second recess.

6. The combination defined in claim 5 wherein said first lug has asloping edge enabling same to be cammed out of said first recess, saidsecond lug having a straight edge holding same positively engaged insaid second recess, said second tongue being provided with camming meansco-operating with said release means to withdraw said second lug fromsaid second recess upon the arrival of the weft carrier at said oppositeside.

7. The combination defined in claim 1 wherein said shed-forming meansincludes a batten provided with a reed traversed by said warp threads,further comprising spaced-apart guides forming a track for said lancesand said weft carriers mounted on said batten at the level of said reed.

8. The combination defined in claim 7 wherein said drive means comprisesa continuously rotating cam shaft for the control of said batten, firstcrank means coupled with said cam shaft for oscillating said firstlance, and second crank means coupled with said cam shaft foroscillating said second lance.

9. The combination defined in claim 8 wherein said first and secondcrank means are relatively dephased for moving said lancescodirectionally and at approximately the same speed upon simultaneousengagement of a weft carrier.

10. The combination defined in claim 8 wherein said drive means furtherincludes a cam coupling between said cam shaft and each of said crankmeans for accelerating said lances within the shed and retarding same inthe vicinity of said sides.

1. In a loom having shed-forming means for a set of warp threads on aframe and a supply of weft threads on one side of the set, thecombination therewith of: a first lance reciprocably mounted on saidframe for introduction into the shedded warp threads from said one sideto substantially the middle of the shed; a second lance reciprocablymounted on said frame for introduction into the shedded warp threadsfrom the opposite side to substantially the middle of the shed; aplurality of weft carriers each provided with weft-gripping means, eachweft carrier having first coupling means engageable by said first lancefor insertion thereby from said one side into the shed and secondcoupling means engageable by said second lance for extraction therebyfrom the shed at said opposite side; drive means for simultaneouslyreciprocating said lance in opposite directions and in alignedrelationship with momentary simultaneous engagement of a weft carrier byboth lances substantially midway of the shed, said second coupling meansoverriding said first coupling means whereby the weft carrier remainsengaged with said second lance upon subsequent separation of saidlances; release means at said opposite side for detaching an oncomingweft carrier from its weft and from said second lance; transport meanson said frame for conveying the detached weft carrier from said oppositeside around said set of warp threads to said one side; and loading meansat said one side for attaching a fresh weft thread to an arriving weftcarrier prior to insertion thereof into the shed by said first lance. 2.The combination defined in claim 1 wherein said weft-gripping meanscomprises a normally closed clamp with a fixed jaw and a movable jaw,said release means including a trip member on said Frame at saidopposite side engageable with said movable jaw.
 3. The combinationdefined in claim 2 wherein said weft carrier is provided with aswingable guard plate extending parallel to its direction of movementacross the shed, said movable jaw being rigid with said guard plate. 4.The combination defined in claim 3 wherein said movable jaw is providedwith spring means urging same toward said fixed jaw while holding saidguard plate in a tilted position in which the weight of said guard platesupplements the force of said spring means.
 5. The combination definedin claim 1 wherein said first coupling means comprises a rearwardly opensocket of the weft carrier provided with a first peripheral recess andwherein said second coupling means comprises a forwardly open socket ofthe weft carrier provided with a second peripheral recess, said firstlance having a tip matingly receivable in said rearwardly open socketand provided with a first tongue carrying a first lug fitting into saidfirst recess, said second lance having a tip matingly receivable in saidforwardly open socket and provided with a second tongue carrying asecond lug fitting into said second recess.
 6. The combination definedin claim 5 wherein said first lug has a sloping edge enabling same to becammed out of said first recess, said second lug having a straight edgeholding same positively engaged in said second recess, said secondtongue being provided with camming means co-operating with said releasemeans to withdraw said second lug from said second recess upon thearrival of the weft carrier at said opposite side.
 7. The combinationdefined in claim 1 wherein said shed-forming means includes a battenprovided with a reed traversed by said warp threads, further comprisingspaced-apart guides forming a track for said lances and said weftcarriers mounted on said batten at the level of said reed.
 8. Thecombination defined in claim 7 wherein said drive means comprises acontinuously rotating cam shaft for the control of said batten, firstcrank means coupled with said cam shaft for oscillating said firstlance, and second crank means coupled with said cam shaft foroscillating said second lance.
 9. The combination defined in claim 8wherein said first and second crank means are relatively dephased formoving said lances codirectionally and at approximately the same speedupon simultaneous engagement of a weft carrier.
 10. The combinationdefined in claim 8 wherein said drive means further includes a camcoupling between said cam shaft and each of said crank means foraccelerating said lances within the shed and retarding same in thevicinity of said sides.